FIGURE 2.

Lymphatic migration occurs in distinct steps. Leukocytes migrate in a stepwise manner from peripheral tissues via afferent lymphatics to dLNs. (1) Interstitial migration: Leukocytes squeeze and migrate through the interstitial ECM. In vicinity of the lymphatic capillaries, they start to sense the peri‐lymphatic CCL21 gradient and begin to directedly migrate toward the vessels. (2) Transmigration into capillaries: Near capillaries, leukocytes squeeze through the thin and discontinuous BM and subsequently transmigrate into the capillary lumen through the open flaps generated between neighboring LECs. (3) Intralymphatic crawling: Once inside the capillaries, leukocytes continue to actively crawl on capillary LECs and patrol the capillary lumen. (4) Passive transport in collectors: Within collecting vessel segments, lymph flow is elevated due to vessel contractions. Once leukocytes have reached this compartment, they start to detach, roll and flow, resulting in rapid transport to the dLN